A method for evaluating the therapeutic efficacy of interferon (IFN)/ribavirin (RBV) for hepatitis C is disclosed. The method includes the steps of providing a specimen mixing the specimen, a primer of a miRNA Let-7g and a poly-chain reaction (PCR) reagent together and evaluating the efficacy of IFN/RBV on inhibiting a hepatitis C virus according to the expressing level of the miRNA Let-7g in the specimen detected by the PCR reagent.